1. Technical Field
The disclosure relates to a technique of discharging residual electric charges of a capacitor when a vehicle including the capacitor that is electrically connected to a rotary electric machine via an inverter is involved in a collision.
2. Description of Related Art
A vehicle that includes: a battery; a boost converter connected to the battery; an inverter connected to the boost converter; a permanent magnet type motor driven by the inverter; a first capacitor connected between paired electric power lines that connect the boost converter and the inverter; and a second capacitor connected between paired electric power lines that connect the boost converter and the battery has been disclosed in Japanese Patent Application Publication No. 2012-100385 (JP 2012-100385 A). When this vehicle collides with a collision target, such as another vehicle or an obstacle, discharge control for discharging residual electric charges of the capacitors is executed by performing a switching operation of the inverter so as to prevent a flow of a q-axis current (a torque current that affects torque) but cause a flow of a d-axis current (a field current that does not affect the torque) to the motor. Then, the inverter is stopped (gate-blocked).
In addition, in view of a fact that the current flows through a motor coil and the electric charges are recirculated in the first capacitor for a while after a stop of the inverter due to electric inertia of the motor coil, the electric charges are distributed not only to the first capacitor but also to the second capacitor by bringing an upper arm of the boost converter into an on state (a conductive state) when the inverter is stopped in the above vehicle. In this way, a boost in an inter-terminal voltage (hereinafter also referred to as a “system voltage”) of the first capacitor, which is caused by the recirculated electric charges during the stop of the inverter, is suppressed.